Removing the last optional parameter from an existing export

As I understand yes, this changes the signature of the service program
and it's the signature it looks at. Just remove it and compile to a test
library and see if the signature has changed. If yes, you have an issue.
If no, you are ok. 

<snip>
I need to remove the last parameter from an existing export procedure,
do I need to recompile programs that uses it?  I've checked all programs
and non of them are passing the last parameter (This is an optional
parameter).
</snip>